The present invention relates to a current source circuit, and more particularly to a current source circuit for producing a plurality of currents with their own weights for use in a digital to analog (D/A) converter, for example.
A D/A converter using R-2R ladder resistors has been fabricated by the IC technology. The D/A converter is based on a principle that a plurality of currents shunted by the R-2R ladder resistors are weighted in accordance with bits, respectively. Since a converting accuracy of the D/A converter using the ladder resistors depends on ratios of resistances of the resistors, it is necessary, for the IC fabrication of the D/A converter, to minimize errors of the shunting resistance ratios by widening the widths of patterns of the shunting resistors. This is undesirable because areas occupied by the shunting resistors on a semiconductor chip are large.